<customer_logout>
            <observers>
                <Jamesckemp_Singlesignon_Model_Observer>
                    <type>singleton</type>
                    <class>Jamesckemp_Singlesignon_Model_Observer</class>
                    <method>CustomerLogout</method>
                </Jamesckemp_Singlesignon_Model_Observer>
            </observers>
        </customer_logout>

<customer_logout>
            <observers>
                <Jamesckemp_Singlesignon_Model_Observer>
                    <type>singleton</type>
                    <class>Jamesckemp_Singlesignon_Model_Observer</class>
                    <method>CustomerLogout</method>
                </Jamesckemp_Singlesignon_Model_Observer>
            </observers>
        </customer_logout>

public function CustomerLogout($observer) {


echo "<form action='https://example.com/logout' method='post' name='logoutt'>";
echo "<input style='visibility: hidden;' type='submit'  name='Submit'>";

            echo "</form>
            <script language="JavaScript">
            document.logoutt.submit();
            </script>";

    }